Hope no one minds me jumping in here, but I think this is actually a Light Arches (Apamea lithoxylaea). There is also Reddish Light Arches, but I think the markings looks better for A. lithoxylaea. They can look very 'wainscot-ish' especially as they get worn.

Yes thats a fair point about the mark, although it looks more like a wear mark to me. The color and steaky appearance and the fact that like Dark Arches, Light Arches can be variable in the degree of markings...my money's on Light Arches still.

A real discussion is just a good place to learn a thing or two, its nice to be able to have them. I've been places for ID's myself and asked 'why is it that you say its that' in order to learn, and some people will just never answer, very frustraiting!